The use of flavored dental floss is known in the prior art. Dental flosses are comprised of either several polymeric fibers combined to form a single strand, or alternatively a single polymeric fiber, or monofilament, and are used to remove bacterial debris and plaque from interdental surfaces otherwise unreachable by conventional toothbrushes.
Although the idea of flavoring dental articles is not new, the solution to the problem of providing a strong, high impact flavor on a monofilament floss, and even more particularly PTFE monofilament, has proved perplexing. Concentrated flavor oils are frequently used in prior art dental flosses for flavor. Such flavor oils are volatile at the high temperatures required to melt common carrier materials (e.g. microcrystalline wax, beeswax and the like) used to coat flosses and thus the impact of the flavor is greatly lost during processing.
U.S. Pat. No. 5,165,913 to Hill et al. describes a coating system for floss involving the use of a saliva-soluble surfactant based carrier which is coated onto a multi-filament floss designed to splay upon use, thus releasing the chemotherapeutic agents carried between the fibers. These chemotherapeutic agents may also consist of flavorants and sweeteners used to enhance the flossing experience. Mentioned sweeteners include xylitol, acid saccharin and sodium saccharin.
U.S. Pat. No. 3,943,949 to Ashton et al. describes the use of spray dried flavor particles, in which flavor oils are dispersed in a water-soluble matrix, in order to protect the oil from degradation and volatilization during processing. The water-soluble matrix containing the flavor oils is applied via water-insoluble waxes, preferably microcrystalline wax, to multi-filament flosses. U.S. Pat. No. 4,033,365 to Klepak et al. also uses spray dried flavor particles consisting of flavor oils dispersed in a water-soluble matrix to add flavor to multi-filament flosses. The coating is polymeric and is solubilized in a volatile organic solvent while the spray dried flavor particles are dispersed therein. The floss is passed through a bath containing solvent, binder and flavor and then the volatile solvent is driven off by heat. With the level of flavor and coatings chosen on the Klepak multifilament substrate, the product would be porous exposing a significant amount of the flavor particles for salvation.
Although water-soluble carriers would be expected to provide the best release of flavor upon contact with saliva during flossing, known water-soluble carriers such as polyethylene glycols tend to have low adherence to standard floss materials including nylon 6 and 66. Thus, other formulations have required two separate coating steps, the first of which deposits a water-insoluble wax or polymeric carrier on the floss surface as a "primer" for a second water-soluble coating containing the volatile flavor oil in order to provide a product with desirable characteristics and good flavor.
U.S. Pat. Nos. 5,226,435 and 5,357,990, both to Suhonen et al., disclose the use of a first coat comprising a high melting temperature wax or polymer, preferably microcrystalline wax, which serves to hold the fibers of a multi-filament floss together and retain the desired shape of the floss while a second coating comprising a lower melting temperature material, preferably a blend of polyethylene glycols containing volatile flavor oil is applied. In addition to the flavor oil, the second coating may contain a sweetener, optimally xylitol, to balance the concentrated flavor oil. The lower melting temperature material is thought to prevent the flavor oil from volatilizing during processing as well as to prevent the melting of the inner coating and preserve the shape of the floss.
Similarly, U.S. Pat. No. 4,414,990 to Yost describes the application of a first wax coating to a multi-filament floss article, followed by a second coating of a polymeric material containing fluoride ions. The first coating optionally contains spray dried flavor particles. The second polymeric coating is said to be "capable of hydration whereby the film so formed is water pervious allowing for rapid release of fluoride salt therefrom." See Yost at Col. 3, lines 18-22.
U.S. Pat. No. 5,353,820 to Suhonen et al. describes a floss comprising a multi-filament texturized yam including an open, porous brush portion with optional threader and/or floss section(s). The article is produced by first applying a polymeric binder coating (preferably nylon) via ethanol solution to the yarn while under tension. Sections of the floss are then exposed to varying degrees of heat, thus driving off varying amounts of solvent, leaving some sections to retract to the original expanded form and the other more heated sections to remain thin and hard. Remaining solvent is then driven off, followed by the application of a second binder coating which contains encapsulated spray dried flavor particles. The second binder should form a water-insoluble coating so as not to dissolve the water-soluble matrix surrounding the flavor particles and should form a hard, flexible polymeric film yet maintain the integrity of the open porous "brush" section of the floss. Polyurethanes soluble in hydrocarbons are preferred. Subsequent applications of the urethane coatings could be made to the optional threader sections to increase the strength of the sections.
Monofilament flosses have become popular among the flossing community due to the reduced amount of fraying and/or shredding associated with them versus multi-filament flosses. In particular, monofilament flosses have been developed using fluorinated polymers such as polytetrafluoroethylene (PTFE) because of the low coefficient of friction (COF) associated with the compounds. The reduced COF allows for easy sliding between tight dental contacts where ordinary multi-filament flosses would perhaps shred or break upon insertion.
Monofilaments, however, are much harder to supply with substantial flavor due to the decreased surface area upon which coating materials can adhere when compared to their multi-filament counterparts. Also, with a monofilament, no splaying of the bundle occurs to expose flavor particles trapped on inner fibers. The surface characteristics of PTFE are not conducive to coating application. U.S. Pat. No. 5,033,488 to Curtis et al. discloses a method for coating expanded, porous PTFE with microcrystalline wax along with oral hygiene actives, coagulating agents, anti-tartar agents and anti caries agents. These additives may also include flavor. The applied coating may also incorporate a water-soluble resin (e.g. polyethylene glycol) in the microcrystalline wax. The coating serves to both increase the COF and to carry the additives.
U.S. Pat. No. 5,503,842 to Fazan et al. mentions in Examples 9-12 a similar coating to U.S. Pat. No. 5,033,488 comprising water-insoluble microcrystalline wax and up to 20% flavorant. The product was deemed to yield "unacceptably low flavorant taste when used." This is due to the fact that the "flavorant in the wax was not solvated so as to provide an acceptable taste." The patent also describes an aqueous emulsion system containing an at least partially water-soluble polymeric binder along with partially water-solubilized medicants and/or flavorants which can be used to coat PTFE or PTFE coated surfaces. The polymeric binder is preferably polyethylene glycol and polyvinyl alcohol. The emulsion is applied to the surface and subsequently dried to remove the water, thus adhering the polymeric binders containing medicants to the PTFE surface. Non-carbohydrate sweeteners such as sodium saccharin and phenylalanine may also be added to the emulsion system.
To improve flavor stability of dental floss, coating formulations have been described whereby spray dried flavors are combined with water-insoluble and water-soluble waxes and coated onto multi-filament yarns. However, no evidence of using flavor enhancers in water-insoluble waxes in coating monofilament yarns, which inherently have a limited surface area, is provided. In order to provide the consumer with a monofilament having a high impact flavor, the coating formulations used must be complex. They typically must contain a water-soluble component and require low process temperatures in order to avoid decomposition of flavor oils. Finally, to provide monofilament dental flosses which deliver sufficient flavor to the consumer, and more specifically for flosses comprising PTFE substrate, the coating compositions used contain significant levels of flavor oils due to the low surface area of the monofilament substrate as compared to a multifilament substrate.
While the above prior art discloses providing flavored dental floss, none of the prior art provides guidance as to a flavored coating composition comprising water-insoluble waxes which provides the consumer with a strong, high impact flavor especially on a monofilament.
It is therefore an object of the present invention to provide a dental article which exhibits a strong, prolonged, high impact flavor.
It is another object of the present invention to provide a dental article having a coating which prevents fraying and/or shredding of the substrate therebelow.
It is a further object of the present invention to provide a dental article that can be easily held (not too slippery) and therefore easily maneuvered between the interproximal spaces of teeth.
It is another further object of the present invention to provide a dental article which can be easily manufactured.
These and other objects and advantages of the invention will become more fully apparent from the description and claims which follow or may be learned by the practice of the invention.